PBN Derived Amphiphilic Spin-Traps. I/Synthesis and Study of Their Miscibility with Polyunsaturated Phospholipids

Abstract

The synthesis of new amphiphilic α-phenyl-N-tert-butylnitrone (PBN) derivatives bearing two hydrocarbon tails with 17 carbon atoms (compound A17) or 11 carbon atoms (compound B11) is reported. The amphiphilic and morphological properties of these potential antioxidant compounds were investigated at the air−water interface. The analyses were conducted using Langmuir film balance and Brewster angle microscopy. As it is possible to obtain pressure−area (π−A) isotherms from pure A17 and B11, this means that they can form stable monomolecular films at the air−water interface. Monolayers of pure PBN derivatives exhibited different interface behavior. Indeed, along with compression, the B11 monolayer showed only a liquid-expanded phase and the A17 monolayer showed a liquid-condensed phase. Brewster angle microscopy showed the presence of condensed domains within the A17 monolayer. The lateral interactions of these compounds with the polyunsaturated phospholipids, 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLoPC) and 1,2-dilinoleoyl-sn-glycero-3-phosphoethanolamine (DLoPE), were evaluated by analysis of π−A isotherms and excess free energy of mixing. Each PBN derivative was miscible with DLoPC or DLoPE and formed nonideal mixed monolayers at the air−water interface. Only the A17 molecules exhibited favorable interactions at high surface pressures (over 20 mN/m) with both DLoPC and DLoPE, however. Under these conditions, A17 should be a better antioxidant than B11.